Service Manuals and Schematics!

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Rasputin
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Re: Service Manuals and Schematics!

Post by Rasputin » Sat Jul 04, 2020 2:37 pm

The rare and elusive Akai Z4 and Z8 service manual and schematics:
http://www.mediafire.com/file/lduhp0tbm ... l.pdf/file

Sorkin Multivox MX3000 Owners Manual (with schematics):
https://mega.nz/file/sZlzFLRI#VktgG5ot1 ... a8eaHfRKbQ

Kawai R50/R50e Service Manual (with schematics):
https://mega.nz/file/wA0h3SaR#dYLOJD_1P ... Gf0SghJL6w

blueknob
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Emu E4K

Post by blueknob » Wed Dec 23, 2020 6:59 am

Anyone know if there is a schematic for the Emu E4K. Mine has a warm up issue with the keyboard part, 8 keys don't work but come into life about 20 mins later and then work perfectly. My guess is a bit/line on the keybed contact scanner chip is failing. It would help to know if it's a replaceable chip or some custom device. The former I can replace. A schematic would help me locate the culprit much faster.

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Yekuku
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Re: Service Manuals and Schematics!

Post by Yekuku » Wed Dec 23, 2020 8:56 am

Hi blueknob, I have uploaded it here :
https://www.sendspace.com/file/8648nc
You can use a hairdryer and a freeze spray to find the culprit.
It is all about sharing...

blueknob
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Re: Service Manuals and Schematics!

Post by blueknob » Wed Dec 23, 2020 11:46 am

Thanks Mr Y - that's very good of you and sooo fast! :drinks:

Had a quick look.. hmm.. once big chip does it all, more.. hmm.. :geek: at least I now know where to look.

thanks again

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Yekuku
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Re: Service Manuals and Schematics!

Post by Yekuku » Wed Dec 23, 2020 12:31 pm

You are welcome blueknob!
A few ideas :
1) check/clean/reattach the fatar keyboard connectors. Replace cable if possible.
2) 8 keys mean that 1 bus has the problem. Could it be due to a leaky diode ? Replace diode on the specific bus.
3) The scanner ic looks like a custom EMU ic, thats bad news.
It is all about sharing...

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Re: Service Manuals and Schematics!

Post by blueknob » Fri Dec 25, 2020 4:53 pm

I studied the circuit, got to the K-Chip emu use for keyboard scanning, worked out exactly which bus line (pair - make and break) - took close look for that specific connector and noticed it was slightly skewed (not in 100% on one end) - pushed it in 1mm. So far all working now :) result.

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Yekuku
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Re: Service Manuals and Schematics!

Post by Yekuku » Fri Dec 25, 2020 6:15 pm

Like a pro ! Good work Blueknob!
It is all about sharing...

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Re: Service Manuals and Schematics!

Post by Gerrymc2010 » Fri Dec 25, 2020 11:57 pm

I'm looking for the Schematic s for the Jen SM2007.

If anyone still has them could I obtain a copy please.

Many Thankx in advance.

G.M

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Re: Service Manuals and Schematics!

Post by Gerrymc2010 » Sat Feb 13, 2021 8:54 pm

oryjen wrote:
Tue May 24, 2016 8:11 am
I found my docs about that JEN SM2007.
If you still need it, please tell me, I can send them to you through email.

Anybody about the KORG 900PS service manual?
Hi Orjen.
Do you still have details of the Jen SM2007.
If so could I obtain a copy.

Thanks

G

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Alesis MicroVerb schematic wanted

Post by blueknob » Sun May 30, 2021 4:48 pm

Alesis Microverb schematic needed - (first generation from 1986 and not the Mk II version).

I got this little beauty new in 1986, (£200) but now on a hot day it decides not to play anymore :(

The analogue parts work (opamps) it's the digital stuff that ain't. For example when the MIX knob is set to DRY the audio gets through fine. When I rotate MIX to "wet" as in all digital reverb... silence, not even noise.

A clue is, from power up it mostly works fine for about 1 second then the digital section goes silent. I'm thinking there might be a wonky reset or mute signal. From what I can tell the PCM54 DAC is doing something sensible (probe with 'scope).
It would help a lot if I had the schematic. This unit has the DASP-16C DSP/CPU. I've found the circuits for similar products but they are using slightly different DSP/CPU chips. eg DASP-8 or DASP-32.

Thanks

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Re: Service Manuals and Schematics!

Post by Yekuku » Mon May 31, 2021 8:24 pm

Hi Blueknob,
unfortunately I dont have the schematics, I was in the same position trying to repair a midiverb II only to realise that there not any schematics available out in the wild.
In my case the problem was a failed DASP CPU, hopefully yours should be ok since the cpu works for a sec, could it be the ram triggering the crash?
Do you have a clean 5V line ? The electrolytics after the rectifier are known to fail.
It is all about sharing...

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Re: Service Manuals and Schematics!

Post by blueknob » Thu Jun 03, 2021 3:21 pm

Thanks Yekuku, you saved me some time. After some study I narrowed the fault down to 3 candidates in the sample and hold cct. So I swapped the source, a 4053 whose output would fall to zero, much to my surprise that didn't fix it. Next is a simple 470pF cap, I swapped that as it was easy, no difference, the only thing left is a TL084. These things never fail... until now :lol: It was such a strange way to fail, it seemed like a dry joint malfunction.

So far the Microverb is working well :D one again I am impressed its reverb quality.

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Yekuku
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Re: Service Manuals and Schematics!

Post by Yekuku » Fri Jun 04, 2021 9:48 am

Good work blueknob!
It is all about sharing...

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Re: Service Manuals and Schematics!

Post by Tekhed66 » Fri Jun 04, 2021 11:36 am

blueknob wrote:
Thu Jun 03, 2021 3:21 pm
Thanks Yekuku, you saved me some time.
Yekuku never fails... always helpful and always has a valuable bit of advice. +1

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